Google Firestore - how to get document by multiple ids in one round trip?

Question

I am wondering if it\'s possible to get multiple documents by list of ids in one round trip (network call) to the Firestore.

Answer 1

Here's how you would do something like this in Kotlin with the Android SDK.
May not necessarily be in one round trip, but it does effectively group the result and avoid many nested callbacks.

val userIds = listOf("123", "456")
val userTasks = userIds.map { firestore.document("users/${it!!}").get() }

Tasks.whenAllSuccess(userTasks).addOnSuccessListener { documentList ->
    //Do what you need to with the document list
}

Note that fetching specific documents is much better than fetching all documents and filtering the result. This is because Firestore charges you for the query result set.